Question 1

What is the minimum bearing for a lintel?

Accepted Answer

The minimum end bearing for lintels in masonry is 150 mm on each side of the opening. This is a Building Regulation requirement under Approved Document A. For spans over 3 m, some manufacturers require 200 mm bearing. The bearing surface must be solid — a full block or brick, not cut pieces. Padstones may be required for point loads on blockwork.

Question 2

How do I choose between steel and concrete lintels?

Accepted Answer

Steel lintels are lighter, easier to handle and available for cavity walls in one piece. They are the standard choice for most domestic openings up to about 4.8 m. Concrete (prestressed) lintels are heavier but cheaper for simple openings and are more common in inner-leaf or solid wall applications. For wide openings or heavy loads, structural steel beams (RSJs) may be needed with a structural engineer calculation.

Question 3

What cavity width steel lintel do I need?

Accepted Answer

Steel cavity lintels are made for specific cavity widths. Common sizes are 50 mm, 65 mm, 75 mm, 90 mm and 100 mm cavity. The lintel cavity must match your wall cavity width. Partial fill insulation may sit within the lintel tray. Full-fill cavities typically use a wider lintel. Always check the manufacturer range for your exact wall build-up.

Question 4

Do lintels need DPC trays above them?

Accepted Answer

Steel cavity wall lintels typically have an integral DPC tray. Concrete lintels in cavity walls need a separate cavity tray DPC installed above them to direct any moisture in the cavity outward through weep holes. Weep holes should be provided at maximum 450 mm centres along the outer leaf above the lintel.

Lintel Length (mm)	Max Opening (mm)	Bearing Each End (mm)
600	300	150
750	450	150
900	600	150
1200	900	150
1500	1200	150
1800	1500	150
2100	1800	150
2400	2100	150
2700	2400	150
3000	2700	150
4800	4500	150

Type	Application	Cavity Widths (mm)	Typical Load
Standard cavity	Windows and doors, outer + inner leaf	50–100	Standard domestic
Heavy-duty cavity	Wide openings, heavy loads	50–100	Heavy or wide spans
Single leaf (angle)	Inner leaf only, internal walls	N/A	Inner leaf or partition
Box lintel	Wide openings, high loads	50–100	Patio doors, bi-folds

Section (mm)	Lengths (mm)	Typical Use	Approx. Weight (kg/m)
65 x 100	600–1800	Internal partitions, non-load-bearing	~15
65 x 140	600–2400	Inner leaf, light loads	~21
100 x 140	600–3000	Inner leaf, standard loads	~33
100 x 215	600–3600	Heavy loads, deep openings	~50

UK Lintel Sizes — Steel & Concrete

Standard Steel Lintel Lengths

Steel Lintel Types

Prestressed Concrete Lintels

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